Calculating Precision to Tolerance Ratio

[breitman]

Hi All,

It has been requested by our customer that we perform precision to tolerance ratio. We currently use GagePack for our MSA studies and are unable to find anything related to this topic. I do understand it pertains to GRR (I hope) but not quite sure where it fits in. I have calculated by hand 6(sigma)/USL-LSL and come up with 162%. Is this even the correct formula? Attached is my sample data.

Any help would be greatly appreciated. Thank you in advance!

 

[Miner]

Re: Precision to Tolerance Ratio?????

Can you explain your data structure? It appears that the different parts are in columns, but are you using 2 operators and 3 replicates or 3 operators with 2 replicates?

The P/T Ratio is the same as R&R as a % of Tolerance.

 

[breitman]

Re: Precision to Tolerance Ratio?????

Hi Miner,
I am using 3 operators with 2 replicates.

 

[breitman]

Re: Precision to Tolerance Ratio?????

I am going scan in my results.

 

[breitman]

Re: Precision to Tolerance Ratio?????

On this doc where the arrow is, is the only thing I see % of tolerance. Which one is it?

 

[Miner]

The Gage R&R (EV+AV) as a % of Tolerance = 3.468 is the P/T Ratio. Looks like you are in great shape.

 

[breitman]

Thank you Miner! Greatly appreciated!

 

[eturkan]

I think your Gage R&R is too good to be true or you are spending $$$$s for a measurement device instead of using a basic caliper.

Check your parts to see if any of them are out of spec.

 

[breitman]

We are using basic calipers. I do have a few parts out of spec, but only because I have been told to use parts that cover the whole tolerance level, and even out of spec. Is this incorrect?

 

[Bev D]

breitman - what are your spec limits?
what is the feature?
what is the data strucure in the excel table you first posted?

with these answers we can provide a more comprehensive answer that addresses your sepcific situation.